The reduced adsorption of lysozyme at the phosphorylcholine incorporated polymer/aqueous solution interface studied by spectroscopic ellipsometry

Coating hydrogel polymers onto solid substrates can reduce the adsorption o f proteins onto these surfaces, but the extent of the reduction in protein adsorption is strongly dependent on how the surface layer is coated. We hav e examined the effect of coating conditions on the structure of thin polyme r films :formed from a number of poly(methacrylate)-based hydrogel polymers via the dip-coating method. We show in this work how the polarity of the s olvent, the speed of lifting, and the annealing temperature affect the thic kness and uniformity of ultrathin phosphorylcholine (PC)-incorporated polym er films coated on the surface of native oxide on silicon and the subsequen t interaction of these coated surfaces with lysozyme molecules. Our results show that the uniformity of the polymer film, and thus the smoothness of t he outer film surface, influence the extent of reduction in protein adsorpt ion. We suggest that the reduction in lysozyme adsorption is the result of a layer of PC groups on the surface of the polymer film. The improvement of the smoothness of the film results in the formation of a close-packed PC l ayer on the outer surface of the polymer film, leaving few defects or cavit ies on which protein molecules can bind. (C) 1999 Elsevier Science Ltd. All rights reserved.